McKim Stephen E, Gäbele Erwin, Isayama Fuyumi, Lambert Jason C, Tucker Lindsay M, Wheeler Michael D, Connor Henry D, Mason Ronald P, Doll Mark A, Hein David W, Arteel Gavin E
Department of Pharmacology, University of North Carolina, Chapel Hill, USA.
Gastroenterology. 2003 Dec;125(6):1834-44. doi: 10.1053/j.gastro.2003.08.030.
BACKGROUND & AIMS: Oxidative stress contributes to early alcohol-induced liver injury, and superoxide (O(2)-) production from NADPH oxidase plays a key role. However, the production of the free radical nitric oxide (NO) by inducible nitric oxide synthase (iNOS) could also be involved.
To test this hypothesis, iNOS knockout (B6.129P2-Nos2 (tm1 Lau)) and wild-type mice were fed high-fat control or ethanol-containing diets for 4 weeks.
Mean body weight gains were not significantly different between treatment groups, and average urine ethanol concentrations were similar in wild-type and iNOS knockout mice. After 4 weeks, serum alanine aminotransferase (ALT) levels were increased significantly about 4-fold over control values (29 +/- IU/L) by enteral ethanol (113 +/- 20) in wild-type mice; this effect of ethanol was significantly blunted in iNOS knockout mice (50 +/- 9). Similar protective effects against liver damage were observed if wild-type mice were treated with the iNOS inhibitor N -(3-aminomethyl)benzyl-acetamindine (1400W). Enteral ethanol also caused severe fatty accumulation, mild inflammation, and necrosis in the liver in wild-type mice but had no effect in iNOS knockout mice. The accumulation of 4-hydroxynonenal (lipid peroxidation) and 3-nitrotyrosine (reactive nitrogen species formation) protein adducts caused by alcohol was completely blocked in iNOS knockout mice.
These data strongly support the hypothesis that iNOS is required for the pathogenesis of early alcohol-induced hepatitis by production of nitric oxide-derived pro-oxidants (e.g., peroxynitrite).
氧化应激导致早期酒精性肝损伤，烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶产生的超氧化物（O(2)-）起关键作用。然而，诱导型一氧化氮合酶（iNOS）产生的自由基一氧化氮（NO）也可能参与其中。
为验证该假设，将iNOS基因敲除小鼠（B6.129P2-Nos2 (tm1 Lau)）和野生型小鼠喂食高脂对照饮食或含乙醇饮食4周。
各治疗组间平均体重增加无显著差异，野生型和iNOS基因敲除小鼠的平均尿乙醇浓度相似。4周后，野生型小鼠经肠道给予乙醇（113±20）后，血清丙氨酸转氨酶（ALT）水平比对照值（29±IU/L）显著升高约4倍；乙醇的这种作用在iNOS基因敲除小鼠中明显减弱（50±9）。如果用iNOS抑制剂N-(3-氨甲基)苄基-乙脒（1400W）处理野生型小鼠，可观察到对肝损伤有类似的保护作用。肠道给予乙醇还导致野生型小鼠肝脏严重脂肪堆积、轻度炎症和坏死，但对iNOS基因敲除小鼠无影响。iNOS基因敲除小鼠中，由酒精引起的4-羟基壬烯醛（脂质过氧化）和3-硝基酪氨酸（活性氮物质形成）蛋白加合物的积累被完全阻断。
这些数据有力支持了以下假设，即iNOS通过产生一氧化氮衍生的促氧化剂（如过氧亚硝酸盐）参与早期酒精性肝炎的发病机制。
